Circuit breaker



Jan. 23, 1934. G. o. WILMS ET AL CIRCUIT BREAKER I Original Filed Nov.1, 1929 Jaw mm? 5 3 4 /2 z vT .l 1 2 i g i 5 2 5 3%? fi A a Q s? 22 w, x9 i I] 6 m J J c, 4 m 0 ow o ww l l ||1||/ O a luw 5 W; 4 1. 2? G Hu .6m H F F Patented Jan. 23, 1934 CIRCUIT BREAKER Gustav 0. Wilms andPanfilo Trombetta, Milwaukee, Wis., assignors, by mesne assignments, toAllen-Bradley Company, Milwaukee, Wis., a corporation of WisconsinApplication November ,1, 1929, Serial No. 403,988 Renewed June 14, 193324 Claims. (Cl. 200--124) This invention relates to a thermal circuitbreaker of the type in which is employed a pawl and ratchet wheel latchhaving the ratchet wheel retained in a fixed position under normalconditions by a fusible binder.

The invention has as an object to provide a circuit breaker which issimple and eiiicient and which is positive and precise in operation.

Another object is to provide a circuit breaker in which the rate atwhich heat is delivered to the fusible binder may be readily adjusted tovary the conditions under which the latch will be released. v

Another object is to provide a circuit breaker which may be readily andeconomically manufactured.

According to the invention in its general aspect and as ordinarilyembodied in practice, the circuit breaker is provided with an electricswitch having a contact arranged in a stationary position and anothercontact arranged upon a movable contact carrier biased to an initialposition, a heat insulated heat conductor extending through the contactcarrier and carried thereby, a ratchet wheel arranged upon one side ofthe contact carrier and retained in a fixed position upon the heatconductor by a fusible binder, a pawl engaging the ratchet wheel andretaining the contact carrier in a predetermined position away from itsinitial position, an electric heater arranged upon the other side of thecontact carrier to generate heat and transmit it through the heatconductor to the binder and thereby release the ratchet wheel.

The invention is exemplified by the circuit breaker illustrated in theaccompanying drawing in which the views are as follows:

Fig. 1 is a top plan view with the top cover plate omitted, showing thecircuit breaker closed and indicating the open position thereof bydotted lines.

Fig. 2 is a sectional front view taken on the line 2-2 of Fig. 1.

Fig. 3 is a bottom plan view with the bottom cover plate omitted.

The circuit breaker has its mechanism arranged within and carried by acasing 1 which is closed at its top by a removable cover plate 2 and atits bottom by a removable cover plate 3.

The cover plates are attached to the casing at one end thereof by a boltor rivet 4 and at the other end thereof by a bolt 5 which may beretracted or withdrawn to permit one or both of the cover plates to bepivoted upon the rivet 4 and provide access to the circuit breakermechanism.

The casing 1 has a terminal 6 and a terminal 7 arranged upon its outsideand electrically connected, respectively, to a spring contact 8 and aspring contact 9 arranged upon its inside.

The spring contacts .8 and 9 are engaged, respectively, by movablecontacts 10 and 11 carried by a pivoted plate or contact carrier 12connected by a pivot 13 to a lug 14 upon the casing 1.

The contact 10 is in continual engagement with the spring contact 8which tends to swing the pivoted plate 12 upon its pivot 13 and movecontact 11 out of engagement with spring contact 9, as shown in dottedlines in Fig. 1.

A heat conductor 15, shown as a tube of high heat conductivity such ascopper, is carried by the pivoted plate 12 and heat insulated therefromby an insulating bushing 16.

A ratchet wheel 1'7 is fixed on the upper end of the conductor 15 by afusible binder 18, such as solder, and normally engaged by a catch orpawl 19 carried by the casing 1 to hold the contacts 10 and 11 inengagement with the spring contacts 8 and 9, respectively.

The binder 18 is adapted to be fused to release the ratchet wheel 1'7and permit the circuit br eakerto open, by heat transferred from anelectric heater which is connected in the circuit to be controlled andarranged in thermal relation with the end of the conductor 15 on theopposite side of the pivoted plate to the ratchet wheel.

The electric heater may take any of the usual forms, such as a coil ofresistance wire, but it is preferably a flat electric heater 20connected between the contacts 10 and 11.

The heater 20 is formed from a fiat strip of 90 resistance material,bent intermediate its ends to form a heating compartment 21, andapertured at its ends to receive the screws 22 and 23 by means of whichit is connected to the contacts 95 10 and 11.

An aperture 24, of greater diameter than the heat conductor 15, isformed in the heater 20 at the top of chamber 21 and the heat conductor15 extends therethrough and into the chamber 21 100 but preferably doesnot contact with the heater 20.

Heat generated by the heater is radiated to the heat conductor 15 andconducted thereby to the fusible binder 18.

When the binder is fused, the spring contact 8 will swing the pivotedplate 12 on its pivot 13 and move the contact 11 out of engagement withthe spring contact 9 to open the circuit, as shown in dotted lines inFig. 1. 110

The binder 18 will then reharden to again bind the ratchet wheel 17 tothe heat conductor 15 in a fixed position thereon.

When the circuit is open, a button 25 on the pivoted plate 12 extendsthrough the front wall or the casing 1 and the circuit may be closed bypressing this button inward to swing the pivoted plate 12 on its pivot13 and bring the contact 11 into engagement with the contact 9.

When a heating coil of resistance wire is employed, the end of the heatconductor 15 is arranged within the coil, but preferably out of contacttherewith, and the heat characteristics of the circuit breaker arevaried by varying the gauge of the wire, the number of turns in thecoil, or the diameter of the coil relative to the diameter of the heatconductor.

When the heater 20 is employed, the heat characteristics of the circuitbreaker may be varied by varying the cross-sectional area of the stripfrom which the heater is formed, the diameter of the aperture 24relative to the diameter of the heat conductor 15, the diameter of theaperture 24 relative to the width of the strip, the width of the chamber21, the depth of the chamber 21, or any combination of such variables.

Regardless of the type heater employed, heat radiated thereby will beabsorbed by the conductor 15 and conducted to the fusible binder 18 toraise the temperature thereof.

Whenever a prohibitive overload occurs or a sufliciently large overloadcontinues for a sufficient length of time, the temperature of the binder18 is raised to the fusing point and then the ratchet wheel 17 releasedto allow the same to rotate on the heat conductor 15.

Heat produced under small and harmless overloads is radiated from theend portions of the heater, the contacts and 11, and the conductor sothat the temperature of the binder 18 is not raised to the fusing point.

Under large or prohibitive overloads, the heat is generated so rapidlyand conducted so quickly to the binder 18 that a sufficient amountthereof cannot be dissipated to delay fusing the binder and the circuitbreaker is opened almost instantly.

Overloads intermediate these two extremes will cause temperature risesin the heater in proportion to the overload and the amount of heatdissipated to delay fusing the binder will be relative to the overload.

The electric heater 20 is readily accessible upon opening the casing onthe side adjacent thereto, and then it may be readily removed from thepivoted plate or contact carrier and replaced either by itself oranother electric heater of different characteristics.

The electric heater which is employed is given characteristicscorresponding to the characteristics of the motor or other appliance tobe protected.

The characteristics which the heater may be given are such that thecircuit breaker will be opened almost instantly upon the occurrence of apredetermined high overload, or only upon the continuance of a loweroverload for a predetermined period. a

The circuit breaker may be adapted to protect any motor by simplyproviding the same with a heater having heat characteristicscorresponding to the characteristics of that motor.

The invention herein set forth is susceptible of various modificationswithout departing from the scope. thereof as hereafter claimed,

The invention is hereby claimed as follows:

1. A circuit breaker, comprising an automatically opening electricswitch having stationary contacts for connection with the circuit to becontrolled, a movable contact carrier having movable contacts arrangedthereon to engage said stationary contacts, an electric heater arrangedupon one side of said contact carrier and connected in series with saidstationary and movable contacts, a heat conductor extending through saidcontact carrier to conduct heat from one side to the other side thereofand having one end in intimate thermal association with said heater, anda ratchet latch arranged upon the opposite side of said contact carrierto said heater to hold said switch closed and having a part thereofretained in a fixed position upon said heat conductor by a fiusiblebinder to keep said latch from being released until said binder is fusedby heat from said heater.

2. A circuit breaker, comprising an automatically opening electricswitch having stationary contacts for connection with the circuit to becontrolled, a movable contact carrier having movable contacts arrangedthereon to engage said stationary contacts, an electric heater arrangedupon one side of said contact carrier and connected in series with saidstationary and movable contacts, a heat conductor extending throughvsaid contact carrier and having one end thereof arranged in thermalrelation to said heater to conduct heat therefrom, a ratchet wheelarranged upon the other side of said contact carrier and retained in afixed position upon said heat conductor by a fusible binder,

and a pawl arranged to engage said ratchet wheel and hold said switchclosed.

3. A circuit breaker comprising an automati cally opening switch forcontrolling an electric circuit, a flat electric heater connected intosaid circuit and having an opening therethrough intermediate the edgesthereof, a heat conductor having a part thereof arranged in saidopening, and a ratchet latch arranged to hold said switch closed andhaving a part thereof retained in a fixed position upon said heatconductor by a fusible binder.

4. A circuit breaker comprising an automatically opening switch forcontrolling an electric circuit, aflat electric heater connected intosaid circuit and having an opening therethrough intermediate the edgesthereof, a heat conductor having one end thereof arranged in saidopening, a ratchet wheel fixed on the other end of said heat conductorby a fusible binder, and a pawl to engage said ratchet wheel and holdsaid switch closed.

5. A circuit breaker comprising an automatically opening switch forcontrolling an electric circuit, a flat electric heater connected intosaid circuit and bent to form a heating compartment, a heat conductorhaving a part thereof arranged in said compartment and a ratchet latcharranged to hold said switch closed and having a part thereof retainedin a fixed position upon said heat conductor by a fusible binderarranged between said latch and said conductor to normally hold saidlatch against relative movement.

6. A circuit breaker comprising an automatically opening switch havingfixed contacts for connection into an electric circuit and movablecontacts to engage said fixed contacts and comiii plete said circuit, anelectric heater connecting said movable contacts and movable therewith,a heat conductor having one end thereof arranged in thermal associationwith said heater to conduct heat therefrom, a ratchet wheel fixed on theother end of said conductor by a fusible binder, and a pawl to engagesaid ratchet wheel and hold said switch closed.

'7. A circuit breaker comprising an automatically opening switch havingfixed contacts for connection into an electric circuit and movablecontacts to engage said fixed contacts and complete said circuit, anelectric heater connecting said movable contacts and movable therewith,a heat conductor having one end thereof arranged in thermal relationwith said-heater to conduct heat therefrom, a ratchet wheel fixed on theother end of said conductor by a fusible binder, a movable support forsaid movable contacts and said heat conductor arranged between saidheater and said ratchet wheel and heat insulated from said heatconductor, and a pawl to engage said ratchet wheel and hold said switchclosed.

8. A circuit breaker comprising two stationary spring contacts. amovable contact carrier, two movable contacts carried by said carrier toengage said spring contacts and close an electric circuit and repelledby said spring contacts to cause one of said spring contacts and itsopposing movable contact to separate and open said circuit, an electricheater connected in said circuit, a heat conductor arranged in thermalrelation with said heater to conduct heat therefrom, a ratchet wheelfixed on said heat con ductor by a fusible binder and spaced from saidheater, and a pawl to engage said ratchet wheel and hold said switchclosed.

9. A circuit breaker comprising two stationary spring contacts, amovable contact carrier, two movable contacts carried by said carrier toengage said spring contacts and close an electric circuit and repelledby said spring contacts to. cause one of said spring contacts and itsopposing movable contact to separate and open said circuit, an electricheater connecting said movable contacts, a heat conductor arranged inthermal relation with said heater to conduct heat therefrom, a ratchetwheel fixed on said heat conductor by a fusible binder and spaced fromsaid heater, and a pawl to engage said ratchet wheel and hold saidswitch closed.

10. A circuit breaker comprising two stationary spring contacts forconnection into an electric circuit, two movable contacts carried by apivoted contact carrier to engage said spring contacts, one of saidspring contacts being in continual engagement with one of said movablecontacts and tending to move said carrier and separate the other twocontacts, a ratchet latch having a part thereof held against relativemovement by a fusible binder to hold said movable con- 'tacts inengagement with said spring contacts, and an electric heater connectedin said circuit to generate heat to fuse said binder and release saidlatch.

11. A circuit breaker comprising two stationary spring contacts forconnection into an electric circuit, two movable contacts carried by apivoted contact carrier to engage said spring contacts, one of saidspring contacts being in continual engagement with one of said movablecontacts and tending to move said carrier and separate the other twocontacts, a ratchet latch having a part thereof held against relativemovement by a fusible binder to hold said movable contacts in engagementwith said spring contacts, and an electric heater connecting saidmovable contacts and adapted to generate heat to fuse said binder andrelease said latch.

12. A circuit breaker comprising two stationary spring contacts forconnection into an electric circuit, two movable contactscarried by apivoted contact carrier to engage said spring contacts, one of saidspring contacts being in continual engagement with one of said movablecontacts and tending to move said carrier and separate the other twocontacts, an electric heater connected in said circuit, a heat conductorhaving a part thereof arranged in thermal relation with said heater toconduct heat therefrom, a ratchet wheel fixed on another part of saidheat conductoriby a fusible binder, and a pawl to engage said ratchetwheel and hold said movable contacts in engagement with said stationarycontacts.

13. A circuit breaker comprising two stationary spring contacts forconnection into an electric circuit, two movable contacts carried by apivoted contact carrier to engage said spring contacts, one of saidspring contacts being in continual engagement with one of said movablecontacts and tending to move said carrier and separate the other twocontacts, an electric heater connecting said movable contacts, a heatconductor having a part thereof arranged in thermal relation with saidheater to conduct heat therefrom, a ratchet wheel fixed on another partof said heat conductor by a fusible binder, and a pawl to engage saidratchet wheel and hold said movable contacts in engagement with saidstationary contacts.

14. A circuit breaker comprising two stationary spring contacts forconnection into an electric circuit, two movable contacts carried by apivoted contact carrier to engage said spring contacts, one of saidspring contacts being in continual engagement with one of said movablecontacts and tending to move said carrier and separate the other twocontacts, an electric heater connected in said circuit, a heat conductorhaving one end thereof arranged within said heater to conduct heattherefrom, a ratchet wheel fixed on the other end of said heat conductorby a fusible binder, and a pawl to engage said ratchet wheel and holdsaid movable contacts in engagement with said stationary contacts.

15. A circuit breaker comprising a casing, spring contacts arrangedwithin said casing and having terminals arranged upon the outside ofsaid casing for connection into an electric circuit, a contact carrierpivoted within said casing, movable contacts carried by said carrier toengage said spring contacts and close said circuit and repelled by saidspring contacts to open said circuit, a heat conductor carried by saidcarrier, a ratchet wheel retained in a fixed position on said heatconductor by a fusible binder, a pawl to engage said ratchet Wheel andhold said movable contacts in engagement with said spring contacts, andan electric heater connected in said circuit and arranged in thermalrelation with said heat conductor to heat the same and fuse said binder.

16. A circuit breaker, comprising a contact, a pivoted plate, a secondcontact carried by said pivoted plate, means for locking said pivotedplate in position so that said second contact engages said firstcontact, means for moving said plate into said locking position,thermally actuated means for releasirfg said locking means uponexcessive flow of current through said contacts, one of said contactsalso comprising spring means for moving said pivoted plate to snap opensaid contacts upon the release of said locking means.

1'7. A circuit breaker, comprising an electric switch tending to beopened by spring action between a movable contact and a stationarycontact, a pawl and ratchet wheel latch associated therewith to keepsaid switch closed under normal current, a fusible binder retaining saidratchet wheel in a fixed position, and an electric heater connected inthe circuit controlled by said switch and arranged to fuse said binderupon an abnormal current through said switch and thereby release saidlatch to permit'said switch to open.

18. A circuit breaker, comprising an electric switch tending to beopened by spring action between a movable contact and a stationarycontact, a pivoted actuator carrying said movable contact, a pawl andratchet wheel latch to keep said switch closed under normal current andhaving said ratchet wheel carried by said actuator and said pawlarranged in a stationary position, a fusible binder retaining saidratchet wheel in a fixed position, and an electric heater connected inthe circuit controlled by said switch and arranged to fuse said binderupon an abnormal current through said switch and thereby release saidlatch to permit said switch to open.

19. A circuit breaker, comprising a self-opening switch, a flat electricheater connected in circuit with said switch and bent intermediate theends thereof to form a heating compartment and having an aperture formedtherein at one end of said compartment, a heat conductor extendingthrough said aperture into said compartment, a ratchet wheel spaced fromsaid electric heater and fixed upon said heat conductor by a fusiblebinder arranged between the same, and a pawl to engage said ratchetwheel and hold said switch closed.

20. A circuit breaker, comprising a supporting frame,-a plate pivotedupon said frame and spring biased toward a given position, an electricswitch having a stationary contact carried by said frame and a movablecontact carried by said plate, a heat insulated heat conductor extendingthrough said plate to conduct heat from one side to the other sidethereof, a ratchet wheel arranged upon one side of said plate and fixedupon said heat conductor by a fusible binder, a pawl carried by saidframe and normally engaging said ratchet wheel to retain said plate in adifferent position, an electric heater connected into an electriccircuit and arranged upon the other side of said plate in intimatethermal association with said heat conductor to generate heat andtransmit the same through said heat conductor to said binder to therebyfuse said binder and release said ratchet wheel upon the pe of anexcessive current through said heater.

21. A circuit breaker, comprising a movable contact carrier providedwith a switch contact engageable with another contact and urged to aninitial position by spring action between said contacts, a heatconductor extending through said contact carrier from one side to theother side thereof and heat insulated therefrom, a ratchet wheel carriedby said heat conductor upon one side of said contact carrier andretained in a fixed position upon said heat conductor by a fusiblebinder, an electric heater arranged upon the other side of said contactcarrier in thermal relation to said heat conductor, and a pawlengageable with said ratchet wheel to retain said contact carrier in apredetermined position away from its initial position.

22. A circuit breaker, comprising a movable contact carrier providedwith a switch contact engageable with another contact, a heat conductorcarried by said contact carrier, an electric heater carried by saidcontact carrier and arranged in thermal relation with said heatconductor, a ratchet wheel retained in a fixed position upon said heatconductor by a fusible binder, and a pawl arranged to engage saidratchet wheel to retain said contact carrier in position to engage saidswitch contacts.

23. A circuit breaker, comprising a movable contact carrier providedwith two movable switch contacts engageable with correspondingstationary contacts, a heat conductor carried by said contact carrier,an electric heater arranged in thermal relation to said heat conductorand connected between said movable contacts, a ratchet wheel retained ina fixed position upon said heat conductor by a fusible binder, and apawl arranged to engage said ratchet wheel to retain said contactcarrier in position to engage said movable contacts with said stationarycontacts.

24. A circuit breaker, comprising a movable contact carrier providedwith two movable switch contacts engageable with correspondingstationary contacts, a heat conductor carried by said contact carrierand extending therethrough from one side to the other side thereof, anelectric heater arranged in thermal relation with said heat conductorupon one side of 'said contact carrier and connected in circuit betweensaid movable contacts, a ratchet Wheel arranged upon the other side ofsaid contact carrier and re- -tained in a fixed position upon said heatconductor by a fusible binder, and a pawl arranged to engage saidratchet wheel to retain said contact carrier in position to engage saidmovable contacts with said stationary contacts.

GUSTAV O. WILMS. PANFILO 'I'ROIVIBETIA.

CERTIFICATE or CORRECTION.

Patent No. 1,944,832; January 23, 1934.

GUSTAV 0. WILMS, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,lines 143, 14.4 and 145, claim 5, strike out the words "arranged betweensaid latch and said conductor to normally hold said latch againstrelative movement"; and that the said Letters Patent should be read withthis correction therein that the same may conform to the record of thecase in the Patent Office.

Signed and sealed this 20th day of March, A. D. 1934.

F. M. Hopkins (Seal) Acting Commissioner of Patents.

